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1、BuildingHigh-levelFeaturesUsingLargeScaleUnsupervisedLearningQuocV.Lequocle@cs.stanford.eduMarc'AurelioRanzatoranzato@google.comRajatMongarajatmonga@google.comMatthieuDevinmdevin@google.comKaiChenkaichen@google.comGregS.Corradogcorrado@google.comJeDeanjeff@google.comAndrewY.Ngang@cs.stanford.
2、eduAbstract1.IntroductionThefocusofthisworkistobuildhigh-level,class-Weconsidertheproblemofbuildinghigh-specicfeaturedetectorsfromunlabeledimages.Forlevel,class-specicfeaturedetectorsfrominstance,wewouldliketounderstandifitispossibletoonlyunlabeleddata.Forexample,isitpos-buildafacedetectorfr
3、omonlyunlabeledimages.Thissibletolearnafacedetectorusingonlyunla-approachisinspiredbytheneuroscienticconjecturebeledimages?Toanswerthis,wetraina9-thatthereexisthighlyclass-specicneuronsinthehu-layeredlocallyconnectedsparseautoencodermanbrain,generallyandinformallyknownasgrand-withpoolingand
4、localcontrastnormalizationmotherneurons."Theextentofclass-specicityofonalargedatasetofimages(themodelhasneuronsinthebrainisanareaofactiveinvestiga-1billionconnections,thedatasethas10mil-tion,butcurrentexperimentalevidencesuggeststhelion200x200pixelimagesdownloadedfrompossibilitythatsomeneuron
5、sinthetemporalcortextheInternet).WetrainthisnetworkusingarehighlyselectiveforobjectcategoriessuchasfacesmodelparallelismandasynchronousSGDonorhands(Desimoneetal.,1984),andperhapsevenaclusterwith1,000machines(16,000cores)specicpeople(Quirogaetal.,2005).forthreedays.ContrarytowhatappearstoConte
6、mporarycomputervisionmethodologytypicallybeawidely-heldintuition,ourexperimentalemphasizestheroleoflabeleddatatoobtaintheseresultsrevealthatitispossibletotrainafaceclass-specicfeaturedetectors.Forexample,tobuilddetectorwithouthavingtolabelimagesasafacedetector,oneneedsalargecollectionofimages
7、containingafaceornot.Controlexperimentslabeledascontainingfaces,oftenwithaboundingboxshowthatthisfeaturedetectorisrobustnotaroundtheface.Theneedforlargelabeledsetsposesonlytotranslationbutalsotoscalingandasignicantchallengeforproblemsw